Multi phase splits. You can use this to time your splits for individual steps of your solving. And you can set this to as many as you want.

Cons:

Sometimes spits out stupid scrambles like 3 movers for 2x2 even when set to WCA mode.

Sometimes a little glitchy overall

Overall I love CSTimer, you can customize it to look however you want and it has lots of handy tools. My person a favorite feature of CSTimer is the keyboard shortcuts. I love keyboard shortcuts for everything I do and being able to switch events or add penalties quicker is great. CSTimer does have a slightly larger learning curve, but once you get used to it I do believe it's the best overall timer. CSTimer also supports mobile, so you can use it on your phone and it actually works surprisingly well. I mentioned that the stackmat feature didn't work in Chrome, and this is due to CSTimer not being https, but the developer has said if you want to use a stackmat with Chrome to use this link: https://cstimer.sinaapp.com/timer.php

Most people who use QQTimer use it because they prefer it's simplistic interface. It might not do a lot, but what it does do, it does very well and it's very reliable. You might not have crazy features, but it's a great timer that many cubers still prefer to use.

Lots of people love Prisma because of it's offline use and ability to store large sessions (10,000+ solves) without much of a problem. Most online timers start to really struggle when you start having a lot of times. They'll start lagging and in some cases you'll have too many solves and need to clear your cache which will erase all your solves. You shouldn't have this problem with Prisma.

Terribly easy scrambles. Often times on 2x2 you'll get several 4 movers in a row

Poor starting timer design

No stackmat support (Even for manually entering times)

TwistTheWeb is honestly pretty terrible. It's only redeeming feature is that fact that you can race your friends. Other than that, it's awful. The scrambles it gives out are ridiculous and should definitely never count towards PBs. You'll also frequently encounter people using fake usernames such as Feliks Zemdegs pretending to be Feliks. So you really can't trust a lot of the people on there.

TNoodleTimer is based off the code used for generating official WCA competition scrambles. While it is a fairly basic time you can rest assured that you will always have a legit scramble and not something ridiculous that shouldn't count. One of the cons is the slow generating time for Square 1 scrambles. Upon initially selecting the event it typically took 30 seconds for the scramble to generate and after a solve it varied. If you're fast at Square 1, you're probably look upwards of a 10 second wait in between scrambles. One thing I do love about this timer is the customizable keyboard shortcuts. As far as I'm aware this is the only timer that does this and I really hope more timers will add it.

Chao TImer doesn't really do anything special, it's just a very simple and clean timer and I have it on my phone just in case I want to use it as a back up or something. But certainly not my first pick.

ZYX timer doesn't do a lot of things very unique, but it does have a couple notable features such as the training tab which no other timer features. Inside the training tab you'll see a list for speed scrambles, OLL practice, PLL practice, and LL practice. So if you are someone who is learning OLL you can go through, select the algs you want to drill, and you'll start the timer, perform the alg, stop it and then it moves onto the next case and helps you drill them. I think this would be a very useful feature for someone just starting out with learning algs. It also has a "global" tab which has algs for 2x2 and 3x3 and from my understanding it's supposed to be user based, but I don't think many people use this feature because there are barely any algs there and I wouldn't even recommend using most of them. And the "play a sound on stop" feature is interesting, but really only useful if you want to annoy your friends. Because quite frankly, it's very silly. But, if playing a fart noise when you stop your timer is your thing, ZYX Timer has your back.

The mobile CSTimer is actually pretty decent, I haven't played with it a lot because I really like the apps that I have, but I think CSTimer for mobile definitely has potential to be the best mobile timer since it'll work on any platform and has all the features of the desktop timer. Definitely worth checking out for Android users.